This invention relates generally to surgically implantable valves. More particularly, this invention relates to devices for the drainage of cerebrospinal fluid from the ventricle of the brain and for monitoring such drainage.
As is well known in the medical arts, to relieve undesirable accumulation of fluids, it is frequently necessary to provide a means for draining a fluid from one part of the human body to another in a controlled manner. This is required, for example, in the treatment of hydrocephalus, an ailment usually afflicting infants or children in which fluids which ought to drain away accumulate within the skull and thereby exert extreme pressure and skull deforming forces.
In treating hydrocephalus, cerebrospinal fluid accumulated in the brain ventricles is drained away by a catheter inserted into the ventricle through the skull. The catheter is connected to a conduit which conducts the fluid away from the brain to be reintroduced into the vascular system, as by extending through the patient's jugular vein to the atrium portion of the heart. To control the flow of cerebrospinal fluid and maintain the proper pressure in the brain ventricle, a pump or valve is placed in the conduit between the brain and the heart atrium. Examples of such pump and valve devices are shown in U.S. Pat. No. 4,560,375, to Schulte et al.
Ventriculostomy reservoirs are often utilized in connection with such pumps or valves to provide a convenient location for sampling accumulated cerebrospinal fluid as close to the brain ventricles as possible. Such ventriculostomy reservoirs may be placed over a burr hole through the skull to facilitate sampling of cerebrospinal fluid before the implantation of the fluid conduit.
Prior ventriculostomy reservoirs typically include a metal base having a catheter connector, an integral, upwardly extending cylindrical wall portion, and a flange portion integrally formed with and overlying the wall portion. A cap made of a silicone elastomer material is typically provided to enclose the upper end of the base and define, with the base, an internal reservoir. The cap usually includes an annular internal recess configured to fit over the flange portion of the base.
The cap and the base of such prior ventriculostomy reservoirs are usually separated prior to implantation. The surgeon, after drilling a burr hole through the skull, attaches a catheter to the connector at the lower end of the base, and then positions the base on the skull. Previously, the surgeon has then been required to grasp the cap and stretch its peripheral edges over the upper flange of the base to position the flange within the recess of the cap. This has, however, presented difficulties for the surgeon which the present invention eliminates.
More particularly, during an operation the surgeon's gloves usually become quite slippery due to contact with blood and other body fluids. This often makes the grasping of objects difficult, particularly when the objects are very small. The caps of prior ventriculostomy reservoirs also tend to become slippery and difficult to handle when they have come in contact with body fluids. This has made it difficult for surgeons to quickly and efficiently grasp and stretch the cap over the upper flange of the base.
Accordingly, there has been a need for a convenient means for attaching the cap of a ventriculostomy reservoir to the base, which renders the device relatively inexpensive to manufacture and which can be constructed substantially of non-metallic parts. Such a device would preferably suffer no degradation in operation within a patient in comparison with prior ventriculostomy reservoirs, and eliminate, as much as possible, handling of the cap separately from the base. In this regard it would be desirable to provide means for connecting the cap to the base in a manner providing a fluid-tight seal therebetween, which required nothing more than for the surgeon to push the cap onto the base at an appropriate time during the surgical procedure. As will become apparent from the following description, the present invention satisfies these needs and provides other related advantages.